900
FXUS63 KJKL 231849
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
249 PM EDT Mon Sep 23 2024

.KEY MESSAGES...

- A potential for showers and thunderstorms will persist through
  much of the next 7 days, largely bringing eastern Kentucky
  beneficial rains after a lengthy period of dry weather for many
  locations.

- The remnants of Potential Tropical Cyclone 9, currently forecast
  to strike the Florida Panhandle as a hurricane late Wednesday,
  may impact parts of eastern Kentucky with an increased chance
  for a widespread yet likely brief rain event late this week.
  However, any flooding potential is likely to be mitigated by the
  likely quick movement of this system.

- High temperatures will climb into the mid 80s today, then trend
  downward through the week.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 248 PM EDT MON SEP 23 2024

The Ohio River and Tennessee River Valleys lie within strengthening
southwest flow aloft between downstream ridging over the Southeast
US and an upstream trough over the Central US. This southwest flow
aloft will amplify through the short-term as the upper trough
deepens and closes off into an unusually strong upper low over the
Ozarks region, with downstream ridging strengthening just off the
Southeast US coast. Multiple disturbances will move through the flow
aloft and support rounds of showers and thunderstorms through
Tuesday night.

For this afternoon, the primary thunderstorm threat will reside
roughly along and south of KY Highway 80 in south-central and parts
of southeastern Kentucky, where effective shear has increased to 25
to 30 kts and instability of 1000-2000 J/kg MLCAPE is expected,
which marginally supports an organized storm threat. The primary
severe threats would be strong gusty winds and large hail, if a
severe storm or two were to develop.

Instability wanes tonight with the loss of daytime heating, which
should greatly limit the severe threat, with showers and storms
continuing to move east and northeast across the area, with the
greatest threat for storms in the south and southwestern parts of
the CWA.

A cold front approaching from the west during the daytime hours
Tuesday will help focus another round of showers and thunderstorms
across central and eastern Kentucky. This round of activity will be
accompanied by 40 to 50 kts of wind shear, with any areas of partial
clearing generating sufficient instability to support scattered
storms, a few of which may be severe, with damaging winds being the
primary threat. Any areas that see repeated rounds of heavy rain may
also see a localized flooding threat.

The aforementioned cold front will track will stall over the Ohio
and Tennessee Valleys, which will keep shower and thunderstorm
chances in the forecast through the overnight Tuesday night. With
the increasingly unsettled weather through the short term,
temperatures, especially highs, will continue an overall downward
trend.

.LONG TERM...(Tuesday night through Sunday)
Issued at 501 AM EDT MON SEP 23 2024

There are two large scale features which will interact with each
other and dominate our weather during the long term period. One of
these is a high amplitude upper trough which will start the
period over the Great Lakes and Mississippi Valley. The other is a
tropical system which will evolve from the area of unsettled
weather currently off the east coasts of Honduras and Nicaragua.
The upper level trough will be drawing on deep mid/upper level
moisture being pulled north from a fetch along the western Gulf
Coast. Precip is expected to be ongoing over at least part of the
area at the start of the period. Models indicate, to varying
extents, a dry slot wrapping around the trough. Because of this
feature, a POP gradient is placed across the JKL forecast area
Tuesday night and Wednesday, with the highest POP in southeast KY
and the lowest in the Bluegrass region. Confidence in the exact
placement of features at that time range is not high, so the POP
pattern represents the best estimate based on the most recent
model runs. The dry slot degrades on Wednesday and Wednesday night
and a more generalized, decreasing POP blankets the area. This
happens as the upper trough develops a pronounced closed upper low
to our west.

By the time we get to Thursday, models suggest the tropical
system will be a hurricane moving north through the Gulf of
Mexico, with its moisture starting to get drawn north around the
extratropical upper low to our west. Both the ECMWF and GFS have
the upper low capturing the tropical system and track its remnants
north through KY on Friday. Have used an increasing POP on
Thursday night as it approaches, with a peak of 60-70% on Friday.
This is influenced by the latest available model runs of the GFS
and ECMWF, and is higher than the latest available national blend
of models.

Once the weakening tropical system departs to the northwest,
models show another dry slot wrapping around the upper low and
reaching us Friday night and Saturday. This results in a relative
minimum in the POP. By the time Sunday rolls around, model
solutions begin to diverge more. The GFS weakens the upper low
and tracks it east over KY, while the ECMWF weakens it but lets it
meander further west. Either way, the dry slot influence would be
waning and the POP creeps a bit higher once again.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
ISSUED AT 127 PM EDT MON SEP 23 2024

VFR conditions are expected to prevail, but possibly interrupted
briefly at times by sub-VFR conditions in showers and
thunderstorms this afternoon and evening. The strongest showers
and thunderstorms are likely to stay along and south of the KY-80
corridor, which makes KSME and KLOZ the most likely locations to
see thunder, followed by KJKL. Additionally, some fog is possible
with any clearing overnight into the morning Tuesday especially
where there is any partial clearing. Winds will be light, except
potentially gusty with any stronger storms.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...CMC
LONG TERM...HAL
AVIATION...CMC